In cohort A, 39 percent of patients achieved a complete remission with incomplete blood count recovery (CRi), and 11 percent achieved a partial response (PR). Median overall survival (OS) was 234 days: 238 days in patients who had received ≤2 prior therapies versus 133 days in those who had received ≥3 prior therapies.

Among the different mutation types in this cohort, patients with the FLT3­-ITD mutation had the highest median OS (238 days) compared with 183 days for FLT3-TKD and 128 days for FLT3-ITD+TKD. Younger patients (<60 years) also had higher median OS than older patients (234 days vs. 183 days).

In cohort B, 10 patients received two or more prior TKIs, and 25 patients acquired FLT3-TKD mutations following TKI exposure:

Dual mutations with FLT3-ITD (n=19)

FLT3-D835 (n=17; ITD=15; D835=2)

The overall response rate in cohort B was 31 percent, with 6 CRis and 5 PRs. Median OS was 94 days: 158 days for those with FLT3-ITD and 63 days for those with dual FLT3-ITD+D835 mutations.

In cohort C, the OS was 55 days, with the authors noting that “these patients had only transient benefit from crenolanib.”